The invention relates to packet data protocol context activation, and more particularly to network-requested packet data protocol context activation.
In the recent years, as services based on the Internet in particular have become increasingly popular, mobile communication systems have been provided with networks for packet-switched data. A General Packet Radio System (GPRS) has been developed for a Global System for Mobile Communications (GSM) to provide GSM mobile stations with a packet-switched data transmission service. Network elements based on the GPRS system will also be applied to a third generation Universal Mobile Telecommunications System (UMTS).
A GPRS network comprises a Gateway GPRS Support Node (GGSN) and a Serving GPRS Support Node (SGSN). The SGSN is responsible for detecting mobile stations capable of GPRS connections in its area, transmitting and receiving data packets to and from the mobile stations, and for monitoring the location of the mobile stations in its service area. The gateway support node GGSN serves as a gateway between the GPRS network and an external Packet Data Network (PDN). The gateway support node GGSN communicates with the data networks through an interface called Gi. Subscriber information is stored in a Home Location Register (HLR).
In order to be able to access GPRS services, a terminal must first make its presence known to the network by carrying out a GPRS attach procedure. This procedure forms a logical link between the terminal and the SGSN, making the mobile station accessible for short message transmission taking place over the GPRS, for paging taking place through the SGSN and for indicating incoming GPRS data. To be more precise, when the terminal MS registers for (attaches to) the GPRS network, i.e. during the GPRS attach procedure, the SGSN creates a Mobility Management (MM) context. User authentication is also carried out by the SGSN in the GPRS attach procedure. In order to transmit or receive GPRS data, the terminal must activate a packet data address it wishes to use by requesting the network to activate a GPRS packet data protocol context, which henceforth will be called a PDP (Packet Data Protocol) context. In connection with the present application, without being restricted to the GPRS system, the term packet data protocol context, or PDP context, refers to any logical connection established in order to transmit packet switched data between a terminal and a network element responsible for the connection, such as a gateway support node.
PDP context activation in the GPRS system makes the terminal known in a corresponding GGSN node, enabling cooperation with external data networks. To be more precise, the PDP context is created at the terminal, in the GGSN and SGSN nodes. The PDP context specifies different data transmission parameters, such as the PDP type (e.g. X.25 or IP), PDP address (e.g. X.121 address), Quality of Service (QoS) and Network Service Access Point Identifier (NSAPI).
The GPRS standard specifies that a network-requested PDP context activation can be actuated. This feature enables the PDP context to be activated from the network. Such a need may arise e.g. when using a so-called push service. The idea underlying a push service is that a subscriber has in advance agreed with a service provider that he or she will automatically, without any separate request, be sent data, e.g. information on stock exchange prices of the day. Also in different telemetric services, the network typically transmits data to a mobile station at long intervals, in which case it is not reasonable to continuously maintain a PDP context, and using a PDP context activated from the network could be an alternative.
The problem with the above-described system is that in principle any one connected to the Internet is able to transmit packets to the GPRS subscriber. Typically, a GPRS subscriber also pays for received packets, which means that the GPRS subscriber may have to pay for packets he or she never wanted.